Electronic scales can be classified primarily into a load cell type using a strain gauge, a tuning fork vibration type using a tuning fork and an electromagnetic balancing type using an electromagnet and an electromagnetic coil.
The load cell type makes weight measurements based on the amount of transformation of the strain gauge by a load to be weighed. As disclosed in a Patent Document 1 hereunder, the tuning fork vibration type makes weight measurements by using the fact that vibration frequency of a tuning fork varies in proportion to a load that is applied between both ends of the tuning fork. On the other hand, the electromagnetic balancing type breaks the balanced condition of a mechanical balance mechanism by a load and recovers the balanced condition by flowing electrical current through the electromagnetic coil, thereby determining the weight of a load based on the amplitude of the electrical current.
As far as precision of these scales is concerned, the tuning fork vibration type and the electromagnetic balance type are higher than the load cell type. On the other hand, in the manufacturing cost of these scales, the electromagnetic balancing type is the highest because of its complex construction and the load cell type is the lowest because of its simplest construction.
Currently, most of platform scales having a weighing range (measurement range) up to 300 kg are the load cell type.